Electrothermic fire alarm



May 14, 1929. P. AMEGLlo ELECTROTHERMIC FIRE ALARM Filed May l2, 1925 2 Sheets-Sheet l a EEE 9 Wl/ff* Gttorucgs. I

May 14, 1929. P. AMEGLIO ELECTROTHERMIC FIRE ALARM Filed may 12,` 1925 2 sheets-sheetA 2 Patented May 14, 1929.

UNITED STATES PATENT OFFICE.

PIETRO AMEGLIO, @E GENOA, ETALY.

ELECTB-OTHERMIC FIRE ALARM.

Application led May l2, 1925, Serial No. 29,840, and in Italy and lGreat Britain May. 13, 1924.

This invention relates to new and useful improvements in electro-thermic fire alarms and has for its principal object the provision of an electric alarm mechanism which includes a normally open electrical circuit and means for closing the circuit responsive to changes in atmospheric temperatures.

In the form ot my invention as disclosed in the accompanying drawings:

Figure 1l is a vertical sectional view of the mechanism.

Figure 2 is a detailed sectional View taken on line 2 2 of Figure 1.

Figure 3 is a horizontal sectional view showing particularly the means for mounting the terminals, and

Figure d is a front elevation.

Referring to the drawings, i invention comprises a box or casing 1 of very thin metal which is secured to Vthe underside of a dial casing 2. The casing 2 includes a base portion 3 having an opening 4 therein. il standard 5 extends upwardly trom the base portion 3 and supports a tubular dial casing 6. Disposed within the opening and forming a closure therefor is a flexible diaphragm 7, having an upwardly extended axially located seat 8. l

Journalled at its respective ends in the dial casing G, and in an insulating bushing 8fL in a metallic disc 8 carried by the casing is a shaft 9 located directly above the seat 8 and having a pinion 10 thereon. The disc 8b is insulated from the casing 6 by an insulating ring 21 interposed between a flange on the disc and the casing, and is secured to the casing by screws 21u insulated from the casing by insulating washers 21h and insulating bushings 21. A lever 11 is ulcrumed as at l2 to the casing 6 and carries a segmental rack 13 which engages the pinion 10. One arm of the lever 11 is pivotally connected as at 14 to the upper end of a rod 15, the lower end of the rod abutting the diaphragm .7 through the medium of the seat A coil spring 16 has its outer' end lixedly connected to the dial casing 6 by a screw 17 and has its other' end ixedly connected to the shaft 9.

,A normally open electrical circuit (not shown) includes two terminals 18 and 19, one of which is grounded on the metallic dial casing 6 and the other of which is insulated therefrom. A metallic bracket 2O is mounted on the disc 8" which is connected to the terminal 1E) by means of a conductor 20a. llournalied in this bracket is a normally stationary cont-act ,arm 22 provided with a contact projection 22a. In this instance the contact arm 22 is in the nature or' a pointer or hand and is fixed to a manually operable sha'tt 23 journalled in the bracketr20 whereby the hand may be turned to any desired angular position and retained in such adjusted position. The shaft 23 is co-axial with the shaft 9 and fixed to the shaft 9 is a movable contact arm 24 provided with a Contact screw 24, which is adapted to engage the relatively stationary contact projection 22, and thereby close the electric alarm circuit.

lt will be observed that I have provided an actuating means which includes a rod having one end pivotally connected to segmental lever 11 and its other end abutting the diaphragm 7, and the spring 16 corinected to the shaft 9 for serving the two functions, viz, yieldaby7 holding the movable arm 2d in relation lo the ixed contact and yieldably holding the rod 15 in engagement with the diaphragm.

ln operation, as the temperature in a room increases due to a tire or the like, the air within the casing 1 will expand and defleet the diaphragm upwardly. This will elevate the rod 15 which will oscillate the lever 11. As a. result, shaft 9 will be rotated and consequently the movable contact arm will be correspondingly rotated. rlhe contact 24L will then contact with the stationary contact 22il and thereby close the alarm circuit- Having now particularly described and ascertained the nature of my said invention and in what manner the 'same is to be performed, I declare that what I claim is in electro-thermic alarm including in combination, a normally open alarm circuit including a fixed wml-.act and a riovablc Contact arm cooperating therewith, a shaft to which the movable arm is ixed, and pressure operating means tor actuating the shaft comprising a closed air chainher having a diaphragm therein, a pinion fixed on the shaft, a piveted lever having a segment engaging the pinion7 a rod having one end pivotally connected t0 the lever and having its other end abutting the diaphragm whereby the red will be nwved longitudinally under the influence of the diaphragm,

and a spring connected to the shaft for yieldably holding the lnevahle arm in spaced relation to the fixed Contact and for yield- 10 ably holding said red in engagement wit-h the diaphragm.

Dated this 13th day 0f May, 1924.

PIETRO AMEGLIO. 

